Just to echo what G said, never have anyone near the tail rotor... Even PVT Gomer Snuffy from Bugtussel, Tennessee who just graduated from basic training and is on his first-ever helicopter ride in FT Hood gets that briefing (actually saw a guy walk into a tail-rotor once... You can't see it if it's spinning and you're behind on line with it). You always approach the bird from an angle where you can see the pilot or peter-pilot. If you can't see him, he can't see you. Not to mention that if one gets hit, he may kick the pedals and swing that boom right around into you and you go home in a bag as chunky salsa... Safety doesn't stop in a combat zone, besides, it's beat into your head from day one around helocopters..
Also, those holes... Three things. First, always thin out the plastic from behind with a steel cutter or some such until you can see light through it, then punch the hole with the tip of your knife, with plastic going into entrance hole, out through exit holes. then after you paint, pick out some silver around the holes to show where the bullet knocked the paint off, esposing the metal underneath... Second, alway be aware of what's behind the holes... The ones you have depecticted are headed straight into the Huey's fuel cell. Third, machineguns and auto-rifles aren't sewing machines. They fire in 3-9 round bursts and they're gonna punch holes in a group, rather than a straight or curved line...
Your diorama overall shows a sense of urgency, but not enough, even for a training excercise, plus there's a big empty space in the lower right corner that needs filling. A couple more figures would really fill it nicely, A crew chief frantically waving the troops onto the bird while a gunner is hosing the PZ would add to the overall drama and urgency. Lastly, The helicopter should be the center of attention. As it is, the story your telling is using the helo as a supporting factor, rather than the main focus. Works in Hollywood becasue of limited camera-angles, and even in boxed dioramas, but not in dioramas where the viewer has a "God's Eye" view of your world...